LED dimming method and LED dimming system

Abstract

The present invention discloses a LED dimming method and a LED dimming system, wherein the LED dimming method comprises the following steps: A: calculating the equivalent current flowing through the LED in accordance with the duty cycle message of the input PWM signal; and B: regulating the current flowing through the LED to the equivalent current. Because the equivalent current flowing through the LED is calculated by the duty cycle message D of the input PWM signal while the duty cycle is not actually regulated, the present invention realizes the aim that the dimming uniformity is improved by linearly regulating the current flowing through the LED. Meanwhile, transformer noise will not be generated because current flows through the transformer in the overall dimming cycle.

I claim: 
     
       1. An LED dimming method comprising the steps of:
 A: Calculating an equivalent current flowing through the LED according to a duty cycle message of an input PWM signal; and 
 B: Regulating a current flowing through the LED to be equal to the equivalent current in the step A without changing an actual duty cycle of the current flowing through the LED. 
 
     
     
       2. The LED dimming method of  claim 1 , wherein in said step B, the process for regulating the current flowing through the LED is achieved by regulating an output voltage by using the equivalent current calculated in the step A as a comparison benchmark, and by comparing the current flowing through the LED with the comparison benchmark to enable the current flowing through the LED to be equal to the comparison benchmark. 
     
     
       3. The LED dimming method of  claim 1 , wherein in said step B, the process for regulating the current flowing through the LED is achieved by calculating a voltage corresponding to the equivalent current, and regulating the LED output voltage according to the corresponding voltage. 
     
     
       4. An LED dimming system comprising:
 an LED; 
 an input module of a duty cycle message, a calculation module of an equivalent current for a duty cycle message which is connected with the input module of a duty cycle message, and a current regulation module which is in controllable connection with the LED and the calculation module of an equivalent current for duty cycle message; 
 said input module of a duty cycle message is used for receiving the duty cycle message of an input PWM signal; 
 said calculation module of an equivalent current for duty cycle message is used for calculating the equivalent current flowing through the LED according to the duty cycle message obtained by the input module of a duty cycle message; and 
 said current regulation module is used for regulating the current flowing through the LED to be equal to the equivalent current calculated by the calculation module of an equivalent current for duty cycle message without changing an actual duty cycle of the current flowing through the LED. 
 
     
     
       5. The LED dimming system of  claim 4 , wherein said current regulation module comprises a voltage regulation module for regulating the LED output voltage, and a comparator;
 said comparator is connected with the LED, the calculation module of an equivalent current for duty cycle message and the voltage regulation module; 
 said comparator is used for comparing the equivalent current calculated by the calculation module of an equivalent current as a comparison benchmark with the current flowing through the LED; and 
 said voltage regulation module is used for regulating the LED output voltage in accordance with the comparison result of the comparator, to enable the current flowing through the LED to be equal to the equivalent current calculated by the calculation module of an equivalent current for duty cycle message. 
 
     
     
       6. The LED dimming system of  claim 4 , wherein said current regulation module comprises a calculation module of an equivalent voltage which is in controllable connection with the calculation module of an equivalent current for duty cycle message, and a voltage regulation module which is in controllable connection with the LED and the calculation module of an equivalent current for duty cycle message respectively;
 said calculation module of an equivalent voltage is used for calculating the voltage corresponding to the equivalent current calculated by the calculation module of an equivalent current for duty cycle message; 
 and said voltage regulation module is used for regulating the LED output voltage in accordance with the corresponding voltage obtained by the voltage regulation module.